The invention is in the field of sensors of position and movement. It relates in particular to a sensor used in the automotive field to measure relative angular displacement of two coaxial rotors, for example mounted on a same transmission shaft.
In the automotive field in particular, there exists a great need for knowing the parameters of operation of all the elements of the motor, for example the position of the controls, the position of the gear lever, the torque applied to the steering shaft, etc. A frequently utilized measurement, for example for the determination of a torque or the adjustment of a cam shaft timing device, is the angular offset between two coaxial shafts.
There is known for example from French patent application No. 99 09397, a magnetic sensor permitting measuring an angular offset between two shafts, applied to the measurement of a torque. However, this device requires, in the case of rotating shafts, an additional system for transmission of information, either by a rotating connector, or by a contactless transmission.
The present invention, which incorporates part of the disclosure of French patent applications Nos. 99 13436 and 99 13437, filed by the applicant, and which are incorporated herein by reference, has for its object to provide an angular offset sensor of a new type, which by its construction does not require such a transmission system.
To this end, the invention provides a contactless analog sensor of angular offset, of the magneto-inductive type, characterized in that it comprises:
a first portion forming a detector, comprising at least one substrate plate carrying at least one flat spiral winding, at least one core layer of a material of high magnetic permeability and low saturation field on at least one portion of said winding, the detector being adapted to coact with a device for processing the electric signal measured at the terminals of the winding,
two rotors each comprising at least one magnet, disposed over a predetermined angular sector, the rotors being movable about a same axis identical to the axis of the winding, each magnet generating in the plane of the core layer a magnetic field of a value higher than the saturation field of said core layer over at least a portion of the surface of the winding.
The description and the drawings which follow permit better understanding the objects and advantages of the invention. It will be clear that this description is given only by way of example, and not in a limiting manner.